Aluminosilicate glasses useful as the lamp envelope for incandescent lamps being operated at elevated temperatures of 500.degree. C. and higher have been known for some time. Aluminosilicate glasses suitable for direct hermetic sealing to molybdenum in the manufacture of other electrical devices such as electronic tubes are also well-known. While said prior art glasses permit lamp operation at the desired elevated temperatures, various problems are still encountered both during lamp manufacture and subsequent lamp operation with the existing glasses. In U.S. Pat. No. 3,310,413, there is disclosed an aluminosilicate glass consisting essentially of in weight percent: 53.5-59.5 SiO.sub.2, 13.0-16.5 Al.sub.2 O.sub.3, 4.0-9.0 B.sub.2 O.sub.3, 8.5-15.0 CaO, 0-5.0 MgO and 5.5-11.5 BaO which is said to provide a liquidus temperature less than about 1125.degree. C. and a viscosity of about 30,000 poises or greater at said liquid temperature in order to prevent the glass devitrification when sealed directly to molybdenum. The desired improvement is attributed to a low MgO content while an undesirably low viscosity at liquidus is said to result from an excess of SiO.sub.2, Al.sub.2 O.sub.3, MgO, CaO or BaO as well as lesser amounts of SiO.sub.2, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, CaO or BaO. An MgO content in the range 1-4% is also said to be needed to achieve a linear coefficient thermal expansion of 46.times.10.sup.-7 cm/cm/.degree.C. between 0.degree. and 300.degree. C. A more recently issued U.S. Pat. No. 4,302,250 discloses an aluminosilicate glass said to be useful for tungsten halogen lamps that require direct hermetic sealing to molybdenum inleads which consist essentially of 64-68% SiO.sub.2, 11-14% CaO, 16.5-18.5 Al.sub.2 O.sub.3, and 2-6.5% SrO+BaO, consisting of 0-4% SrO and 0.5% BaO. It is again required that said glass exhibit a liquidus temperature below 1300.degree. C. along with a viscosity of 30,000 poises at said liquid temperature in order to avoid glass devitrification when the glass tubing employed in lamp manufacture is initially formed. A strain point of at least 750.degree. C. is also said to be required to avoid stress in the glass-to-metal seals during lamp operation. Some BaO is said to be needed in said glass to prevent excessive liquidus temperatures although an amount greater than 5% by weight is said to produce strain points which are too low and coefficients of thermal expansion which are too high.